Securing and quickly releasing heavy tensile loads is crucial to safety and success in industries as wide-ranging as commercial fishing, oilfield operations, aerospace operations, barge tugging, and movie special effects. Considering the variety of conditions that tools employed for securing the loads must operate, characteristics, such as shape and size, of these tools can vary greatly, but the tools ideally should have two consistent qualities. First, the tools must be able to safely secure an anticipated tensile load. Second, the tools must allow the release of the tensile loads when necessary. Unfortunately, these qualities are hard to balance for tools designed to secure tensile loads of a significant weight.
Conventionally, the greater a weight of a load secured by a tool is, the more effort is necessary to release the load and the longer the release process takes. For example, pelican hooks and pin-shackles can handle tensile loads of a significant weight, but were not designed to be released while still under load; as a result, the effort necessary to release these tools rises sharply with the weight of the load. The same situation exists even with tools that were designed to be released under load, and typically, with loads exceeding eight tons, the effort to manually release a tool begins to exceed what a normal person is capable of accomplishing.
An example of the tool that was designed for being released while under load can be found in U.S. Pat. No. 5,901,990, issued May 11, 1999, to John H. McMillan, the disclosure of which is incorporated by reference. The U.S. Pat. No. 5,901,990 patent describes an improved toggle locking release mechanism that includes a connecting body, an opposing pivoted jaw, moveable lock/release links, and a moveable release lever. The mechanism uses pivoting of the lever on a fixed toggle pivot to control movements of the jaw and to lock and release the load secured by the mechanism. While the described mechanism offers numerous improvements over pre-existing devices, the mechanism still requires efforts of more than one person to release the load once the weight of the load reaches a certain amount. For instance, once the weight of the load approaches eight tons, the effort to release the load becomes about 65 kilograms, which is beyond the capacity of most people to apply. As the weight of the load continues to increase, releasing the load secured by the mechanism can require either specialized tools or coordinated efforts of multiple people; thus, the effort to release a load weighing about 77 tons using the mechanism can approach 640 kilograms. Considering that the use of the tools and coordinating the efforts of multiple people may not be easily achievable under harsh conditions, such as during a storm at sea, the use of the mechanism may not be practicable in certain situations. Similarly, while one can potentially reduce the effort necessary to unlock the mechanism by increasing the length of the moveable lever, an increase sufficient enough to allow one person to release the load secured by the mechanism may make the mechanism impracticably large.
Accordingly, there is a need for a tool that can secure high-tensile loads and that requires less effort to release the load than conventional tools.